U.S. patent number 4,921,363 [Application Number 07/330,930] was granted by the patent office on 1990-05-01 for thermal transfer printer having independent carriage scanning mechanism and ribbon winding motor.
This patent grant is currently assigned to Sharp Kabushiki Kaisha. Invention is credited to Testuo Nishihara, Tomotaroh Tohjyoh, Takashi Watanabe.
United States Patent |
4,921,363 |
Nishihara , et al. |
May 1, 1990 |
Thermal transfer printer having independent carriage scanning
mechanism and ribbon winding motor
Abstract
An improved thermal transfer printer which is so arranged that a
winding motor for driving a transfer ribbon winding device in
synchronization with a carriage motor is mounted on the carriage
separately from the carriage motor so as to reduce the load applied
onto the carriage motor, with simultaneous elimination of an
engaging mechanism between a carriage scanning mechanism and the
ribbon winding device.
Inventors: |
Nishihara; Testuo (Osaka,
JP), Watanabe; Takashi (Nara, JP), Tohjyoh;
Tomotaroh (Nara, JP) |
Assignee: |
Sharp Kabushiki Kaisha (Osaka,
JP)
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Family
ID: |
27519447 |
Appl.
No.: |
07/330,930 |
Filed: |
March 27, 1989 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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106027 |
Oct 8, 1987 |
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818137 |
Jan 13, 1986 |
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Foreign Application Priority Data
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Jan 26, 1985 [JP] |
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60-12864 |
Jan 26, 1985 [JP] |
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60-12865 |
Jan 26, 1985 [JP] |
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60-12866 |
Jan 26, 1985 [JP] |
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60-12867 |
Jan 26, 1985 [JP] |
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60-12868 |
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Current U.S.
Class: |
400/120.16;
347/197; 347/214; 400/185; 400/208; 400/225; 400/229; 400/249 |
Current CPC
Class: |
B41J
33/22 (20130101); B41J 33/34 (20130101); B41J
35/36 (20130101) |
Current International
Class: |
B41J
35/36 (20060101); B41J 33/14 (20060101); B41J
33/22 (20060101); B41J 33/34 (20060101); B41J
003/20 () |
Field of
Search: |
;400/120,194,195,196,196.1,207,208,208.1,225,229,249 ;346/76PH |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0077218 |
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Apr 1983 |
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EP |
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0063494 |
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Apr 1983 |
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JP |
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0102782 |
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Jun 1983 |
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JP |
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009889 |
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Jun 1984 |
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JP |
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Other References
IBM Technical Disclosure Bulletin, "Optical Means for End-of-Ribbon
Sensing", Bullock et al, vol. 23, No. 9, Feb. 1981, pp. 3955-3956.
.
IBM Technical Disclosure Bulletin, "End-of-Ribbon Sensor and
Cartridge-Present Indicator", Jenkins, vol. 27, Nov. 1984, pp.
3645-3646..
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Primary Examiner: Wright, Jr.; Ernest T.
Attorney, Agent or Firm: Birch, Stewart, Kolasch &
Birch
Parent Case Text
This application is a continuation, of application Ser. No.
07/106,027 filed on Oct. 8, 1987, now abandoned, which is a
continuation of application Ser. No. 06/818,137 filed on Jan. 13,
1986, now abandoned.
Claims
What is claimed is:
1. A thermal transfer printer comprising:
a carriage having a ribbon supply reel and a ribbon winding reel
for supporting a thermal transfer ribbon, and a thermal head for
transferring data to a recording medium through said thermal
transfer ribbon by heat generation, said carriage being displaced
transversely across a recording medium by a carriage motor;
a transfer ribbon cassette detachably mounted on said carriage,
said cassette including a ribbon supply spool and a ribbon winding
spool respectively engaged with said ribbon supply reel and said
ribbon winding reel, the thermal transfer ribbon passing around
said supply spool and said winding spool;
cassette detecting means, provided on said carriage, for detecting
said transfer ribbon cassette;
a winding motor, provided independently of said carriage motor, for
selectively driving said ribbon winding reel in synchronization
with said carriage motor, said winding motor being responsive to
said cassette detecting means for enabling rotation of said ribbon
winding reel only when said transfer ribbon cassette is
detected;
means for selectively impressing said thermal head against said
recording medium;
said means for selectively impressing said thermal head against
said recording medium being operative at the start of recording,
and said winding motor beginning rotation of said ribbon winding
reel before said means for selectively impressing said thermal head
against said recording medium, said carriage motor and said winding
motor being driven in synchronization with each other upon
impressing said thermal head against said recording medium;
said means for selectively impressing said thermal head being
further for spacing said thermal head from said recording medium
upon completion of recording, said carriage motor terminating
rotation and said winding motor continuously rotating said ribbon
winding reel until completion of the spacing of said thermal head
from said recording medium and being stopped upon completion of
said spacing, said carriage motor being continuously driven
thereafter.
2. The thermal transfer printer according to claim 1, wherein said
means for selectively impressing is operative in response to a
control circuit which directs the continuous rotation of said
ribbon winding reel by said winding motor until said thermal head
is completely spaced from said recording medium, said control
circuit continuing the operation of said carriage motor subsequent
to said thermal head being completely spaced from said recording
medium.
3. A thermal transfer printer according to claim 1, further
comprising a control means for changing-over heat generating
temperatures of said thermal head according to the detection by
said cassette detecting means, so as to set the heat generating
temperature of said thermal head during a transfer recording period
mounted with said cassette, lower than that during a recording
period onto a heat sensitive recording medium, not mounted with
said cassette.
Description
BACKGROUND OF THE INVENTION
The present invention generally relates to a thermal transfer
printer and more particularly, to a supply arrangement of a thermal
transfer ribbon for a serial thermal transfer printer so arranged
that a carriage detachably mounted with a thermal transfer ribbon
cassette is subjected to a horizontal scanning with respect to a
recording paper. The thermal transfer printer is capable of
selectively effecting a transfer recording onto plain paper through
mounting of the thermal transfer ribbon cassette, or a recording
onto a heat sensitive paper without mounting the thermal transfer
ribbon cassette.
Conventionally, in the thermal transfer printer as referred to
above, it has been so arranged that the thermal transfer ribbon fed
out from a supply spool is brought into pressure contact with the
recording paper between a thermal head and the recording paper. The
thermal transfer ribbon is subsequently wound onto a winding spool
which is engaged with a scanning mechanism of a carriage for
rotation to take up the thermal transfer ribbon thereon. There have
not been provided means for detecting the presence or absence of
the thermal transfer ribbon, or means for controlling heat
generating temperatures for the thermal head according to the
result of the detection by the detecting means.
In the known thermal transfer printer as described so far, however,
since the carriage motor serves as a driving source for the
displacement of the carriage and also for winding the thermal
transfer ribbon, the load becomes undesirably large, with a
consequent requirement for a motor of a large size. Moreover, the
engaging mechanism between the scanning mechanism of the carriage
and the winding spool tends to be complicated, and readjustments
are frequently required by the characteristic changes of mechanical
elements such as springs, wires, etc. through operations for long
periods of time. Meanwhile, in the prior art thermal transfer
printer as described above, since the thermal transfer ribbon
winding means is not required to be driven during recording onto
the heat sensitive paper, it becomes necessary to provide means for
releasing engagement thereof with the carriage scanning means, thus
also resulting in a further complication of the engaging mechanism.
Besides, since no means are provided for controlling heat
generating temperatures of the thermal head through detection of
whether or not the thermal transfer ribbon is attached, there has
been such a problem that it is difficult for the thermal head to
achieve a proper temperature during either one of the thermal
transfer print mode or the recording mode using heat sensitive
paper, or during both of these modes.
Furthermore, in the conventional thermal transfer printer, owing to
the arrangement that the transfer ribbon winding means is rotated
through engagement with the scanning mechanism driven by the
carriage motor, upon stopping displacement of the carriage
according to the completion of recording, the transfer ribbon
winding means stops rotating, and in this case, if the winding of
the transfer ribbon is suspended before completion of spacing of
the thermal head from the recording paper, the transfer ribbon
tends to be loosened or slackened when the thermal head has been
completely spaced from the recording paper.
Another disadvantage inherent in the known thermal transfer printer
is such that, since it is so arranged that a pressure contact
mechanism of the thermal head is driven at the start of the
recording so as to bring the thermal head into pressure contact
with the recording paper, and thereafter, the carriage motor is
driven to displace the carriage, with the transfer ribbon winding
means being rotated by said carriage motor, the winding of the
transfer ribbon is effected after completion of the pressure
contact of the thermal head, but is not effected during functioning
for the pressure contact of the thermal head, and thus, slackening
of the transfer ribbon takes place in this case also.
SUMMARY OF THE INVENTION
Accordingly, an essential object of the present invention is to
provide an improved thermal transfer printer which is so arranged
that a thermal transfer ribbon winding motor, independent of a
carriage scanning mechanism, is mounted on a carriage for
exclusively winding the thermal transfer ribbon for substantial
elimination of disadvantages inherent in the conventional thermal
transfer printers as referred to earlier.
Another important object of the present invention is to provide a
thermal transfer printer of the above described type in which
driving of the thermal transfer ribbon winding motor is controlled
through detecting the presence or absence of the thermal transfer
ribbon as mounted so that when the ribbon is not mounted, the
winding motor can not be driven for winding purposes.
A further object of the present invention is to provide a thermal
transfer printer of the above described type in which there is
provided a control means for controlling the heat generating
temperature of the thermal head by detecting the presence or
absence of a transfer ribbon cassette as mounted so as to
change-over the heating temperature of the thermal head between the
thermal transfer print mode and the recording mode to a heat
sensitive paper, for providing the temperature suitable to each
case.
Still another object of the present invention is to provide a
thermal transfer printer of the above described type in which the
thermal transfer ribbon winding motor provided independently of the
carriage scanning mechanism is rotated until completion of spacing
of the thermal head from the recording paper so as to be stopped in
rotation after complete spacing of the thermal head therefrom to
prevent the slackening of the transfer ribbon.
A still further object of the present invention is to provide
thermal transfer printer of the above described type in which the
thermal transfer ribbon winding motor provided independently of the
carriage scanning mechanism is controlled to be driven before the
thermal head contacts the recording paper under pressure at the
start of recording. In other words, in the course of the
functioning for the pressure contact so as to prevent the transfer
ribbon from slackening, the carriage motor is controlled to be
driven in synchronization with the winding motor during pressure
contact of the thermal head onto the recording paper so as to
prevent the slackening of the transfer ribbon at the start of
recording.
In accomplishing these and other objects, according to one
preferred embodiment of the present invention, there is provided a
thermal transfer printer which has a carriage provided thereon with
a supply means and a winding means for a thermal transfer ribbon
and a thermal head which effects transfer onto a recording paper
for recording by heat generation, with the carriage being arranged
to be displaced by a carriage motor in a direction intersecting at
right angles with a recording paper feeding direction for recording
through the thermal transfer ribbon, and which comprises a transfer
ribbon cassette detachably mounted on the carriage and
accommodating therein a ribbon supply spool and a ribbon winding
spool respectively engaged with said supply means and said winding
means and the thermal transfer ribbon passed around said supply
spool and winding spool, a cassette detecting means provided on the
carriage for detecting mounting of the transfer ribbon cassette,
and a winding motor provided independently of said carriage motor
so as to drive the winding means in synchronization with said
carriage motor, whereby the driving of said winding motor is
controlled according to the detection by said cassette detecting
means so as not to rotate said winding means when the transfer
ribbon cassette is not mounted.
There is also provided a control means for changing-over heat
generating temperatures of said thermal head according to the
detection by said cassette detecting means, so as to set the heat
generating temperature of said thermal head during a transfer
recording period mounted with said cassette, lower than that during
the recording period onto a heat sensitive paper, not mounted with
said cassette.
The above thermal transfer printer according to the present
invention further includes a pressure contact/spacing mechanism for
selectively contacting the thermal head under pressure with the
recording paper or spacing said thermal head therefrom, and a
control circuit means which effects control in such a manner that
it drives said pressure contact/spacing mechanism for the thermal
head in synchronization with the rotation of said winding motor
until completion of a recording, and continuously rotates said
winding motor until completion of spacing of said thermal head so
as to stop rotation of said winding motor after the completion of
the spacing and for driving said carriage motor thereafter.
Further provided in the above thermal transfer printer of the
present invention is a control circuit means which effects control
in such a manner that it drives said pressure contact/spacing
mechanism for the thermal head so as to bring said thermal head
into pressure contact with the recording paper at the start of
recording, with said winding motor being started before the
pressure contact of said thermal head, with said carriage motor and
said winding motor being driven in synchronization with each other
during said pressure contact.
By the arrangement according to the present invention as described
above, advantages as follows are available.
(i) By providing on the carriage, the winding motor for driving the
transfer ribbon winding means in synchronization with the carriage
motor, independently of said carriage motor for displacing the
carriage, the load for the carriage motor is reduced, while the
engaging mechanism between the carriage scanning mechanism and
ribbon winding means has been made unnecessary.
(ii) By the control means for controlling the winding motor,
carriage motor and thermal head functioning motor, the transfer
ribbon can be prevented from slackening.
(iii) By changing-over the heat generating temperature of the
thermal head according to presence or absence of the transfer
ribbon cassette as mounted, the temperature of the thermal head may
be maintained at a proper level both for the thermal transfer
recording by the transfer ribbon, and for the recording onto a heat
sensitive paper.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects and features of the present invention will
become apparent from the following description taken in conjunction
with the preferred embodiments thereof with reference to the
accompanying drawings, in which:
FIG. 1 is a perspective view of a thermal transfer printer
according to one preferred embodiment of the present invention;
FIG. 2 is a perspective view showing on an enlarged scale, the
internal construction of a carriage employed in the thermal
transfer printer of FIG. 1;
FIG. 3 is a perspective view showing on an enlarged scale, a
thermal head employed in the printer of FIG. 1;
FIG. 4 is a perspective view of a thermal transfer ribbon cassette
to be applied to the printer of FIG. 1;
FIG. 5 is an electrical block diagram showing the circuit
construction of the thermal transfer printer of FIG. 1;
FIGS. 6(a) through 6(3) are flow-charts showing sequence of
functions of the thermal transfer printer of the present invention;
and
FIGS. 7(a) and 7(b) are diagrams showing correlations among driving
states of respective motors for the thermal transfer printer
according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Before the description of the present invention proceeds, it is to
be noted that like parts are designated by like reference numerals
throughout the accompanying drawings.
General construction (FIG. 1)
Referring now to the drawings, there is shown in FIG. 1, a thermal
transfer printer according to one preferred embodiment of the
present invention, which generally includes a chassis 10, a platen
14 rotatably provided along one side of the chassis 10, a paper
feeding motor 20, and a carriage 30 to be described in more detail
later and provided with a ribbon supply reel 32, a ribbon winding
reel 31, a thermal head 35, a ribbon end sensor 37 composed of a
photoelectric element, an actuating lever 38 projecting through a
carriage cover plate 39 and associated with a cassette mounting
sensor 70 composed of a microswitch (FIG. 2) provided in the
carriage 30.
The chassis 10 of a generally rectangular configuration includes a
base portion 9, side walls 11 and 12 extending upwardly from
opposite sides of the base portion 9, and a front panel 13 also
extending upwardly from the front side of said base portion 9, with
rear half portions of said side walls 11 and 12 being formed to be
higher than front half portions thereof. The platen 14 is rotatably
supported, at opposite ends of its shaft 15, by the rear half
portions of said side walls 11 and 12, while a pair of guide shafts
16 and 17 for guiding the carriage 30 to travel therealong are
fixed, at opposite ends thereof, to the front sides of said side
walls 11 and 12 so that said shafts 16 and 17 are laterally
supported in a parallel and spaced relation to each other. A lower
paper guide plate 18 is also supported by the side walls 11 and 12
to extend from the lower portion of the platen 14 toward its rear
portion through a predetermined interval from the surface of said
platen 14, while at the back of said guide plate 18, the paper
feeding motor 20 consisting of a stepping motor is fixed to the
side wall 11. A motor gear 21 is fixed on a rotary shaft 21a of
said motor 20 extending outwardly from the side wall 11, and is
engaged with one of idler gears 22 of a double construction. The
other gear (not shown) of said idler gears 22 is in mesh with a
platen gear 23 fixed to the corresponding end of said platen shaft
15, whereby the platen 14 is rotated through rotation of the paper
feeding motor 20 for feeding a recording paper 8 in a vertical
direction. The recording paper 8 may be either plain or heat
sensitive.
Between the guide shafts 16 and 17 described above, in a relation
parallel therewith, a timing belt 28 is passed around pulleys 24
and 25 respectively provided on the base portion 9, with the
opposite ends of said timing belt 28 being secured to the carriage
30. The pulley 25 is integrally formed with an idler gear 26, which
is engaged with a motor gear 27 fixed to a rotary shaft 107(a) of a
carriage motor 107 (FIG. 5) consisting of a stepping motor and
provided on the chassis 10.
Accordingly, the timing belt 28 is moved through rotation of the
idler gear 26 and pulley 25 by the rotation of the carriage motor
107, and according to the movement of said timing belt 28, the
carriage 30 is subjected to reciprocating movements along the guide
shafts 16 and 17. In FIG. 1, recording to the recording paper 8 is
effected during movement of the carriage 30 in the rightward
direction.
Construction of carriage cover (FIG. 1)
Through the cover plate 39 which covers the open upper face of the
carriage 30 in a rectangular flat box-like configuration, the
ribbon supply reel 32 and ribbon winding reel 31 project from a
gear box 30B formed internally of said carriage 30. From the rear
side of said cover plate 39, a paper guide plate 36 extends
upwardly to have an arcuate cross section concentric with the
peripheral surface of said platen 14. The cover plate 39 is
arranged to have mounted thereon a transfer ribbon cassette 40 as
shown in FIG. 4, and guide members 33 and 34 for mounting the
cassette 40 are provided to project from central portions of the
front and rear sides of the cover plate 39, with the forward guide
member 33 being formed by a plate spring. Moreover, the ribbon end
sensor 37 consisting of a photoelectric element is provided to
project through the cover plate 39 so as to be inserted into the
ribbon cassette 40 to be mounted for detection thereof, for
example, through utilization of the light transmitting property of
the ribbon end portion 47A. Furthermore, the actuating lever 38 of
the cassette mounting sensor 70 provided within the gear box 30B
formed internally of carriage 30 is also adapted to project through
the cover plate 39 from the lower portion so that the cassette
mounting is detected by the function of the sensor 70 through
contact of said actuating lever 38 with the bottom plate 40(a) of
the cassette 40 to be mounted, while the non-mounting of the
cassette 40 is detected when the lever 38 is not actuated.
Description of the thermal head (FIG. 3)
The thermal head 35 in the shape as shown in FIG. 3 is mounted on
the carriage 30. More specifically, a head support plate 67 of the
thermal head 35 is mounted on the carriage 30 through an axis 68
for rotation about said axis 68, while a spring 69 is stretched
between the support plate 67 and the carriage 30 so as to urge the
thermal head 35 in a direction indicated by an arrow in FIG. 3,
i.e., in the direction away from the platen 14. A head slider 66
having a generally L-shaped cross section is fixed to the head
support plate 67, and by vertically moving said head slider 66 with
a driving unit 61 (to be described later) provided in the carriage
30, the thermal head 35 is brought into complete pressure contact
with the platen 14 at the uppermost position of the head slider 66,
while the head 35 is spaced away from the platen 14 at the
lowermost position thereof.
Construction of transfer ribbon cassette (FIG. 4)
In the transfer ribbon cassette 40 to be mounted on the carriage
cover plate 39, a ribbon supply spool 41 wound with a transfer
ribbon 47 and engaged with the ribbon supply reel 32, and a ribbon
winding spool 42 engaged with the ribbon winding reel 31, are
rotatably supported. The transfer ribbon 47 wound around said
ribbon supply spool 41 and led out from said supply spool 41 passes
through a cut-out portion 45 in which the thermal head 35 and the
guide member 34 are inserted, via three guide pins 44A, and is
subsequently taken up onto the winding spool 42 through three guide
pins 44B. Accordingly, by rotating the winding spool 42 in the
counterclockwise direction through rotation of the ribbon winding
reel 31, the transfer ribbon 47 is led out from the supply spool 41
into the cut-out portion 45, i.e., into the recording portion. The
cassette 40 is formed in its bottom plate 40(a), with a hole 43
through which the ribbon end sensor 37 referred to earlier is
inserted into the cassette 40.
Internal construction of carriage (FIG. 2)
In the carriage 30, there are provided a supply reel unit 50, a
winding reel unit 56 and a pressure contact/spacing mechanism,
i.e., a driving unit 61 provided between said reel units 50 and 56
for selectively contacting or spacing the thermal head 35 with
respect to the platen 14 and consequently, to the recording paper
8.
The supply reel unit 50 includes a reel shaft 51, clutch plates 52
and 53 having a felt member 54 sandwiched therebetween, and a
spring 55, with the supply reel 32 referred to earlier being formed
by extending the upper portion of the reel shaft 51. The supply
reel 32, reel shaft 51 and clutch plate 53 are integrally formed,
and are rotatably supported by an inner shaft 32A erected on the
base plate 30(a) of the carriage 30. Meanwhile, the other clutch
plate 52 is pressed against the clutch plate 53 by the spring 55 so
as to be fixed without rotating, to thereby constitute a tension
mechanism for the reel 32. Accordingly, the supply spool 41 of the
cassette 40 is rotated by overcoming the frictional force of the
felt member 54 when the transfer ribbon 47 is led out. Moreover, by
the friction of the felt member 54, supply of an extra amount of
the transfer ribbon 47 due to rotation by inertia is prevented. The
ribbon winding reel 31 also has the similar construction to the
above supply reel 32, but the clutch plate 52 in the supply reel 32
is replaced by a winding gear 57. This winding gear 57 is engaged
with a motor gear 60 mounted on a rotary shaft 110(a) of a winding
motor 110 (FIG. 5) consisting of a stepping motor and mounted on
the carriage 30 through an idler gear 57a located at the back of
the winding gear 57. Therefore, by the clockwise rotation of said
winding motor 110, the winding gear 57 is rotated in the direction
of the arrow, and the ribbon winding spool 42 is rotated in the
counterclockwise direction through the winding reel 31, with said
winding spool 42 being driven in synchronization with the carriage
motor 107 for displacing the carriage 30.
The rotation of the above winding gear 57 has a torque larger than
an adhering force by which the transfer ribbon 47 adheres to the
paper 8 for recording so as to pull off the ribbon 47 and also to
prevent slackening of said ribbon 47. Meanwhile, the amount of
rotation of said winding gear 57 is set to be larger than the
amount of rotation of the carriage motor 107, i.e., the amount of
displacement of the carriage 30. Although the winding of the
transfer ribbon 47 is suppressed by the pressure contact of the
thermal head 35 with respect to the platen 14, since the winding
motor 110 has an amount of rotation larger than that of the
carriage motor 107, the winding gear 57 is idly rotated by
overcoming the frictional force of the felt member 54 for the
winding reel unit 56. Accordingly, the frictional force of this
felt member 54 must be set to be larger than the adhering force of
the transfer ribbon 47, but smaller than the pressure contact force
of the thermal head 35 so that the transfer ribbon 47 does not
unnecessarily slide over the recording paper 8.
In the driving unit 61 for contacting or spacing the thermal head
35 with respect to the platen 14, a cam gear 62 is rotatably
journalled on the carriage bottom plate 30a, while gear teeth are
formed on the peripheral face of the cam gear 62, with a
cylindrical cam 63 being further formed on the upper surface of
said cam gear 62. The gear teeth of the cam gear 62 are engaged,
through an idler gear 64, with a motor gear 65 provided on a rotary
shaft 109(a) of a head functioning motor 109 (FIG. 5--not shown in
FIG. 2) consisting of a stepping motor and mounted on the bottom
portion 30a of the carriage 30. The forward end of head slider 66
integral with said thermal head 35 is held in pressure contact with
the cam protrusion 63a of said cylindrical cam 63. The cam
protrusion 63a is gradually increased in its height to provide a
sharp notched portion 63b subsequent to its highest position, and
when the head slider 66 is located at the highest position of the
cam protrusion 63a through rotation of the cam gear 62, the thermal
head 35 is brought into pressure contact with the platen 14, and
when said head slider 66 is positioned at the lowest position
(i.e., on the flat surface of the cam gear 62), the thermal head 35
is spaced away from the platen 14. Simultaneously, as described
earlier, the thermal head 35 is urged to be spaced from the platen
14 by the spring 69.
In the above construction, during the recording, by rotating the
head functioning motor 109, the thermal head 35 is brought into
pressure contact with the platen 14, while during non-recording
periods such as the returning and spacing periods, by further
rotating the head functioning motor 109, the thermal head 35 is
rapidly spaced from the platen 14 so as to displace the carriage
30, with the above state maintained. Meanwhile, within the carriage
30, the cassette mounting sensor 70 referred to earlier and
consisting of a microswitch for detecting the mounting of the
transfer ribbon cassette 40 is provided, with its actuating lever
38 projecting through the carriage cover 39. By the function of
said cassette mounting sensor 70, change-over is effected between
the control of recording by utilizing the thermal transfer ribbon
47 and the control of recording through the recording paper 8 of a
heat sensitive type, and the driving of the winding motor 110 is
adapted to be suspended when the cassette 40 is not mounted.
Circuit construction (FIG. 5)
Referring also to FIG. 5, the construction of the system control
circuit for the thermal transfer printer according to the present
invention will be explained hereinafter.
The system control circuit shown in FIG. 5 generally includes a CPU
(central processing unit) 100, a ROM (read only memory) 101, a RAM
(random access memory) 102, an interface 115, an output I/O port
104, and an input I/O port 105 which are all connected to a system
bus 103, a drive control 106 connected to the output I/O port 104
and also to the carriage motor 107, paper feeding motor 20, head
functioning motor 109, winding motor 110 and further to the thermal
head 35 through a head drive circuit 111, with the ribbon end
sensor 37 and cassette mounting sensor 70 being coupled to the
input I/O port 105 as shown.
The CPU 100 effects the system control on the entire printer
according to the system programs as shown in FIGS. 6(a) to 6(d)
preliminarily stored in the ROM 101, which are sequentially read
out by the CPU 100. The RAM 102 is subjected to control for the
data read-out or write-in by the CPU 100, and this RAM 102 includes
an area 102a for recording the recording data from a host computer
90, and various registers, counters, flags, etc. for the control
formed therein. The interface device 115 is intended to effect data
transmission or reception with respect to the host computer 90 such
as a centro-interface, and is supplied with characters or image
data equivalent to one line or predetermined lines for storing in
the data area 102a of the RAM 102 through the system bus 103. The
output I/O port 104 applies data to the respective motors (i.e.,
the carriage motor 107, paper feeding motor 20, head functioning
motor 109 and winding motor 110) and also, to the driving circuit
111 of the thermal head 35 based on the control by the CPU 100. The
input I/O port 105 takes in the signals from the ribbon end sensor
37, cassette mounting sensor 70 and other key signals (not
particularly shown) for input to the CPU 100. The drive controller
106 for controlling driving of the respective motors 107, 20, 109
and 110 and the thermal head 35 applies exciting pulses of various
phases to the motors 107, 20, 109 and 110 consisting of stepping
motors based on the control data from the CPU 100, and also
supplies respective recording dot data to the head driving circuit
111.
By the above control, the winding motor 110, carriage motor 107,
and head functioning motor 109 are adapted to bring the thermal
head 35 into pressure contact with the recording paper 8 by
starting the head functioning motor 109 according to the starting
of the recording, and before completion of the pressure contact of
said thermal head 35, the winding motor 110 is driven for rotation
so as to prevent the slackening of the transfer ribbon 47, and upon
completion of the pressure contact of the thermal head 35, the
carriage motor 107 is adapted to be driven for rotation in
synchronization with the winding motor 110.
Meanwhile, the winding motor 110, carriage motor 107 and head
operating motor 109 space the thermal head 35 away from the
recording paper 8 by driving the head functioning motor 109 in
synchronization with the rotation of the winding motor 110
according to the termination of continuous recording, while the
winding motor 110 is continuously rotated until the spacing of the
thermal head 35 has been completed so as to prevent the slackening
of the transfer ribbon 47, and upon completion of the spacing of
the thermal head 35, the rotation of the winding motor 110 is
interrupted, for subsequently driving the carriage motor 107.
The head driving circuit 111 includes a shift register 111a having
a capacity equivalent to the number of dots for the thermal head
35, and a buffer 111b connected in parallel with this shift
register 111a and coupled to a switching circuit 111c of a group of
heat generating elements 111d. In the thermal head 35 driven
through the driving circuit 111, the heat generating elements 111d
are arranged, for example, longitudinally in one row.
When the transfer ribbon cassette 40 is not mounted, the energizing
time for the heat generating elements 111d is made longer than when
the cassette 40 is mounted so as to increase the heat generating
temperature of the thermal head 35. It is to be noted here that in
order to raise the heat generating temperature of the thermal head
35, the voltage applied to the heat generating elements 111d may be
increased instead of lengthening the energizing time therefor.
Functions FIGS. 6 and 7
Subsequently, referring particularly to FIGS. 6(a) through 7(b),
functions of the thermal transfer printer of the present invention
as described so far will be explained.
When data are ready, with a recording data for one line being
stored in the memory data area 102a of the RAM 102 from the host
computer 90 through the interface device 115 (FIG. 5), procedures
in FIG. 6(a) are effected as follows to start the recording
functions.
In FIG. 6(a), in S1 it is first checked whether the cassette
mounting sensor 70 is on or off, and if it is in the off state, the
mode is set for the recording of the ordinary heat sensitive paper
8, while if judged as on, the transfer print flag is set to be on
in S2. Moreover, in S3 judgement is made as to whether the ribbon
end sensor 37 is on or off, and if it is on, it is judged in S4
that the transfer ribbon 47 within the transfer ribbon cassette 40
has been all used up to effect the error processing, e.g., sounding
of an alarm and lighting of a lamp, without carrying out the
recording function. For the recording onto the heat sensitive paper
8, the heat sensing temperature is higher than that of the thermal
transfer ribbon 47, and thus, in the case of the heat sensitive
paper 8, it is necessary to set the heat generating temperature of
the thermal head 35 to be high, and therefore, the energizing time
is increased for the purpose.
Subsequently, in S5 the initial drive control of the head
functioning motor 109 and the winding motor 110 is effected. By
this control, the head functioning motor 109 is rotated to bring
the thermal head 35 into pressure contact with the platen 14, while
the winding motor 110 is rotated to apply a constant tension to the
transfer ribbon 47 for removal of slackening. The above control of
the winding motor 110 is effected only during the transfer print
mode in S6, and does not function during the heat sensitive paper
printing mode.
As shown in FIG. 6(b) marked with * .circle.1 as continuous from
FIG. 6(a), the specific functions are such that in S7 a CD value
equivalent to the amount of rotation until the thermal head 35
completely contacts the platen 14 is set in the counter 102b in the
RAM 102. For the above, in S8 the head functioning motor 109 is
rotated until the head slider 66 contacts the highest portion of
the cylindrical cam 63 of the cam gear 62 in FIG. 2. Thereafter,
also in S8, exciting pulses are fed to the head functioning motor
109 through the output I/O port 104 and the drive control 106, and
further, such exciting pulses are continuously fed through counting
down by "one" of the CD value in S9 until the relation CD.ltoreq.i
in S10 is reached. This state is shown in FIG. 7(a)-A. Here, the
value i is equivalent to the point in time immediately before the
thermal head 35 completely contacts the platen 14, and equivalent
to about 10 steps prior to actuation of the stepping motor 20. In
the case of the transfer print mode, exciting pulses are fed also
to the winding motor 110 from the above state as shown in S12 and
S13 for repetition until the relation CD=0 in S11 is reached. This
state is shown in FIG. 7(a)-B. It is to be noted here that, for
each of the motors (the head functioning motor 109, winding motor
110, and carriage motor 107) in FIGS. 7(a) or 7(b), the time-chart
for one phase is shown, in which the initial exciting pulse is
adapted to be broader than other exciting pulses in order to
increase the torque for the rising. By the above series of
functions, the thermal head 35 is brought into complete pressure
contact with the platen 14, while the winding spool 42 does not
wind up the ribbon 47 unnecessarily, with the slackening of said
ribbon 47 being simultaneously prevented.
Referring back to FIG. 6(a), the procedure advances to the
recording function. Prior to the recording, it is judged whether or
not the mode is the transfer print mode as shown in S6, and in the
transfer print mode, it is checked whether the cassette mounting
sensor 70 (see S14) and the ribbon end sensor 37 (see S15) are on
or off, and in the case where the cassette mounting sensor 70 is
off or the ribbon end sensor 37 is on, the error processing is
executed in S16 to effect the returning of the carriage 30 as
described later for suspending the recording function. This
function is intended to interrupt the recording in the case where
the cassette 40 is carelessly removed during the recording or the
ribbon 47 is terminated.
If the conditions as described so far are satisfied, the recording
is executed in S17, and the recorded data of the RAM 102 are read
out, and the judgement of the skip command in S18 (idle feeding of
the thermal head 35) and line feed (LF) command in S19 (carriage
returning command) is effected. In the case of the recording data,
one column of the recording data is transferred to the shift
register 111a of the head drive circuit 111 in S20 for recording in
S21 by energization of the heat generating elements 111d of the
thermal head 35.
As illustrated in FIG. 6(c) marked with * .circle.2 as continuous
from FIG. 6(a), the specific functions are such that, in the case
of the transfer print mode at S22, the PL value equivalent to heat
sensing temperature of the transfer print mode, the PL value
equivalent to heat sensing temperature of the thermal transfer
ribbon 47, is set at S23 in the counter 102b within the RAM 102,
while, if the mode is not the transfer print mode, the PH value
equivalent to the heat sensing temperature of the heat sensitive
paper 8 is set therein (PL<PH) at S24. Moreover, the strobe
signal is fed out to transfer the data of the shift register 111a
to the buffer 111b of the head driving circuit 111 in S25, and in
the heat generating elements 111d of the thermal head 35, the
elements 111d in which the recording dot data are present, are
energized for starting the recording. Thereafter, are energized for
starting the recording. Thereafter, the PH value or PL value is
counted down by "one" in S26 for repetition until the relation
PH(L)=0 is reached in S27. In other words, the time for
energization is determined by the value of PH(L), and upon arrival
at the relation PH(L)=0, the above buffer 111b is reset at S28 to
terminate the energization for completion of the recording.
Referring back to FIG. 6(a) again, upon completion of the recording
by the above functions in FIG. 6(c), the carriage motor 107 and the
winding motor 110 are controlled for rotation in S29 to displace
the carriage 30 to the subsequent column position, while the amount
of the ribbon 47 removed by the above displacement, in the transfer
ribbon 47 held between the thermal head 35 and the platen 14, is
wound up to be pulled off the recording paper 8.
The above functions continue to FIG. 6(d) marked with * .circle.3
as continuous from FIG. 6(a).
In the first place, exciting pulses are fed to the carriage motor
107 and the winding motor 110 (only during the transfer print mode)
in S30. Moreover, the CL value representing the amount of
displacement of the carriage 30 is counted up by "one" in S31 until
C=1 in S32 (further described below). Here, exciting pulses are
applied also to the winding motor 110 by the same step as that for
the carriage motor 107 in order to impart a torque to the winding
reel 31 to such a degree as is sufficient for separating the
transfer ribbon 47 from the recording paper 8 due to the fact that,
since the gear ratio of the motor gear 60 in FIG. 2, idler gear 57a
and winding gear 57 is set to be slightly larger than that of the
carriage motor gear 27 and the idler gear 26 in FIG. 1, the amount
of rotation of the winding gear 57 becomes larger than the amount
of displacement of the carriage 30. By the above torque, a
predetermined tension is applied to the ribbon 47, while, by the
frictional force of the felt member 54 under the winding gear 57, a
torque larger than the pressure contact force of the thermal head
35 is absorbed so that the ribbon 47 may not be wound up
unnecessarily. Therefore, the ratio in the amount of rotation of
the above motors 107 and 110 during one column is not limited to
1:1, but based on the above gear ratios, the exciting pulse supply
rate for the winding motor 110 may be made smaller than that for
the carriage motor 107 to achieve the torque relation as described
above.
Reverting to FIG. 6(a), the above functions are repeated until the
recording equivalent to one line at S33 has been completed. In FIG.
7(a)-C, in the case where the recording equivalent to one line,
i.e., the LF command in the recording data is read out, or the
carriage 30 has been displaced up to a predetermined position,
control for the remaining amount of rotation for the carriage motor
107 and the winding motor 110 is effected. This function is
intended to idly feed the thermal head 35 by a predetermined amount
so as to separate the transfer ribbon 47 adhering to the recording
paper 8.
The above functions continue to FIG. 6(d) as marked with *
.circle.4 . When the relation CL=1 at S32 (wherein 1 is the
position at the end of the line for the predetermined recording
range) is reached or the LF command is read out, a CE value
equivalent to the above separation or peeling-off control and the
removal of slackening is set at S34 in the counter 102b within the
RAM 102. Subsequently, exciting pulses are fed out to the carriage
motor 107 and the winding motor 110 (only during the transfer print
mode) in S35 so as to count down the CE value by "one" in S36, and
also to count up the CL value by "one" in S37. This function is
continued until arrival at the relation CE=i' in S38 (FIG. 7(b)-D).
The above value i' is equivalent to the amount of displacement by
which the recording dots are deviated from the pressure contact
portion of the thermal head 35, and is equivalent to about 10 dots.
Thereafter, the carriage motor 107 is stopped and exciting pulses
are fed out to the winding motor 110 (only during the transfer
print mode) and the head functioning motor 109 at S39, the CE value
is counted down by "one" in S40 until arrival at the relation CE= 0
(FIG. 7(b)-E) in S41. In this case, since the head slider 66
directly contacts the lowest portion of the cam protrusion of the
cylindrical cam 63, the thermal head 35 is momentarily spaced from
the platen 14 so as to be subsequently rotated up to a home
position of the cylindrical cam 63, and in this case, the winding
motor 110 is rotated to remove the slackening amount.
It should be noted here that in the above series of functions,
although the carriage 30 is displaced by the amount equivalent to
the separation, the function for E may be directly effected without
effecting the above function. In this case, however, there is a
possibility that the ribbon 47 is taken out from the supply spool
41 more than necessary, since the winding motor 110 applies a
torque equivalent to the separating force, thus inviting such
problems that the adjustments of the degree of tension of the
supply reel 32, and of the winding torque become complicated.
Referring back to FIG. 6(a), rotation control of the carriage motor
107 and the paper feeding motor 20 is subsequently effected in S42,
and thus, the returning function of the carriage 30 and feeding of
the predetermined amount of the recording paper 8 are completed in
S43.
More specifically, the function continues to FIG. 6(e) as marked
with * .circle.5 , and the exciting pulses in the opposite phase
are supplied to the carriage motor 107 in S44 until the CL value
reaches zero, while exciting pulses equivalent to the predetermined
paper feeding amount CF value are fed to the paper feeding motor
20.
In other words, the predetermined paper feeding value is set as
C.sub.F SET in S45 and the paper feed and carriage return function
of paper feed motor 20 and carriage motor 107 are "ON",
respectively, in S46. With both of these motors "ON", exciting
pulses are fed out to these motors in S47 so as to count down the
C.sub.F value by "one" in S48 and to count down the C.sub.L value
by "one" in S49. These functions are continued until the paper feed
value is zero (i.e. C.sub.F =0) at S50 thereby turning the paper
feed OFF until arrival at the relation C.sub.L =0 in S51 thereby
turning the carriage return function of the carriage return motor
OFF. The process continues until both motors are OFF as in S52.
Reverting again to FIG. 6(a), when the skip command is read out
from the recording data, the control for the remaining rotation for
the carriage motor 107 and winding motor 110, and the terminating
rotation control of the head functioning motor 109 and the winding
motor 110 are effected according to the flow-chart of FIG.
6(d).
Thereafter, exciting pulses are fed to the carriage motor 107 so as
to displace the carriage 30 by the number of skips read out as the
recording data, and thus, the thermal head 35 is idly fed without
recording the non-recording region (space) and without effecting
the winding.
As is clear from the foregoing description, in the thermal transfer
printer according to the present invention, since the winding motor
110 for driving the transfer ribbon winding unit 56 in
synchronization with the carriage 30 is provided on the carriage 30
separately from the carriage motor 107 for displacing said carriage
30, the load to be applied to the carriage motor 107 is
advantageously reduced therefore requiring only a compact size
motor 107. Moreover, since the engaging mechanism between the
carriage scanning mechanism and the transfer ribbon winding unit 56
becomes unnecessary, there are such advantages that not only the
mechanism is simplified, but adjustment of such engaging mechanism
is not required. Meanwhile, by effecting the winding of the ribbon
47 by the winding motor 110 in synchronization with the printing,
stable feeding of the transfer ribbon 47 may be effected.
Furthermore, since driving of the winding motor 110 is made
impossible except for during the transfer print mode, noises
arising from idle rotation of the winding reel 31 are lowered,
while loss of electric power can be reduced. The thermal transfer
printer of the present invention may be applied to a color printer
having various color components in a serial form.
Meanwhile, according to the thermal transfer printer of the present
invention, owing to the arrangement that the means for detecting
the presence or absence of the transfer ribbon cassette 40 as
mounted, i.e., cassette detecting means 38,70 is provided so as to
control the ribbon winding motor 110 according to the result of
detection by said detecting means 38,70, the driving of the winding
motor 110 is automatically suspended during non-mounting as in the
case where the cassette 40 is carelessly dismounted, while when
non-mounting of the cassette 40 is detected, the error display (see
FIG. 6a) is effected to make other motors also inoperable without
starting of the recording function, and thus, non-mounting of the
cassette 40 may be quickly noticed.
Moreover, in the thermal transfer printer of the present invention,
the heat generating temperature of the thermal head 35 is changed
over for control according to the result of detection by the
cassette detecting means 38,70, whereby the heat generating
temperature of the therm head 35 is set to be lower in the transfer
print mode employing the transfer ribbon 47 than that in the
recording mode onto the heat sensitive paper 8, and thus, it is
possible to adjust the heat generating temperature of the thermal
head 35 to an optimum level according to each mode. Owing to the
arrangement that the engaging mechanism between the carriage
scanning mechanism and the transfer ribbon winding means is made
unnecessary by providing the ribbon winding motor 110 separately
from the carriage motor 107, it is not required to release the
engagement of such engaging mechanism during recording onto the
heat sensitive paper 8, and thus, the construction and function are
simplified.
Furthermore, according to the thermal transfer printer of the
present invention, since it is so arranged that the thermal head 35
is brought into pressure contact with the recording paper 8 through
driving the functioning motor 109 of the thermal head 35 according
to the starting of the recording by the control circuit (see FIG.
5), with the winding of the transfer ribbon 47 being effected
before completion of the pressure contact, i.e., by rotating the
winding motor 110 in the course of the function for the pressure
contact, slackening of the transfer ribbon 47 at the starting of
the recording can be prevented.
Additionally, owing to the arrangement that the thermal head 35 is
spaced away from the recording paper 8 by driving the thermal head
functioning motor 109 in synchronization with the winding motor 110
according to the completion of the continuous recording through the
control circuit means (see FIG. 5), while the winding motor 110 is
continuously rotated until completion of the spacing to wind up the
transfer ribbon 47 so as to stop rotation of the winding motor 110
after completion of said spacing of the thermal head 35, the
transfer ribbon 47 is also prevented from slackening.
Although the present invention has been fully described by way of
example with reference to the accompanying drawings, it is to be
noted here that various changes and modifications will be apparent
to those skilled in the art. Therefore, unless otherwise such
changes and modifications depart from the scope of the present
invention, they should be construed as being included therein.
* * * * *